While many companies have phased out the IBM mainframe, there are still many legacy applications are still running that have been difficult to convert to client/server technology.  Cloud & Java based apps can now run on the mainframe, as IBM has been constantly improving this technology over time.

https://www.eweek.com/pc-hardware/ibm-reinvents-the-z-mainframe-again

QUOTE:   Reports of the imminent demise of IBM’s Z mainframes, the company’s flagship enterprise system platform, have been floated–only to plummet ignominiously earthward–for more than a quarter-century or nearly half of the time the mainframe has been commercially available. In essence, the reason that the mainframe has thrived for well over a half century is because IBM has reinvented it time and again.

With its new Tailored Fit Pricing models, IBM is clearly onto something good. A notable point about both models is that discounted growth pricing is offered on all workloads–whether they be 40-year old Assembler programs or 4-day old JavaScript apps. By making access to Z mainframes more flexible and cloud-like, IBM is making it less likely that customers will consider shifting Z workloads to other systems and environments

So how is IBM addressing these issues? With Z mainframe software pricing that one company executive described as “Two sizes fit most.” They are:

1. Enterprise Capacity Model: Designed for clients that require operational simplicity and complete cost predictability but who also expect substantial workload growth. Pricing is based on past usage and growth patterns and is priced at a consistent monthly rate. Essentially, this model is discounted full capacity.

2. Enterprise Consumption Model: Supports highly-flexible, container-based (cloud-like) consumption and billing. The client makes monthly license charge (MLC) and million service usage (MSU) baseline commitments, but built-in annual entitlements and reconciliation processes reduce or eliminate seasonal variability issues. Also includes aggressive (~50% price/performance) pricing for MSUs as application usage grows.